The Pharmaceutical Resources Branch, Division of Cancer Treatment, National Cancer Institute, desires to obtain quantities of radiolabeled materials. Laboratories for the procurement of these radiolabeled materials are to be maintained and operated. Such radiolabeled materials are used for preclinical and clinical studies. Specific assignment of the radiolabeled materials for procurement will be made by the National Cancer Institute and may include all types of chemicals and drugs containing a variety of radioactive atoms with the major emphasis being on the preparation of the desired labeled materials via synthetic procedures using carbon-14 and tritium. Development of synthetic methods and process development will be required. All materials must be assayed by the Contractor for chemical and radiometric identity and purity.